Micro device arrangement in donor substrate

ABSTRACT

This disclosure is related to arranging micro devices in the donor substrate by either patterning or population so that there is no interfering with unwanted pads and the non-interfering area in the donor substrate is maximized. This enables to transfer the devices to receiver substrate with fewer steps.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of U.S. patent application Ser.No. 16/684,820, filed on Nov. 15, 2019, now allowed, which is a divisionof U.S. patent application Ser. No. 15/696,700, filed on Sep. 6, 2017,now U.S. Pat. No. 10,535,546, issued on Jan 14, 2020, which claims thebenefit of and priority to U.S. Provisional Patent Application No.62/403,741, filed on Oct. 4, 2016, and Canadian Patent Application No.2,941,038, filed on Sep. 6, 2016, each of which is hereby incorporatedby reference herein in its entirety.

FIELD OF THE INVENTION

The present disclosure relates to the integration of a transferred microdevice system on a receiver substrate. More specifically, the presentdisclosure relates to patterning micro devices on a donor substrate andthe landing area on a receiver substrate to increase the efficiency ofthe transfer process.

SUMMARY

A few embodiments of this description relate to patterning micro deviceson the donor substrate to facilitate a selective transfer process. Themicro device array may comprise micro light emitting diodes (LEDs),organic LEDs, sensors, solid state devices, integrated circuits, MEMS(microelectromechanical systems), and/or other electronic components.Other embodiments are related to patterning the placing of micro devicesin respect to pixel arrays to optimize microdevice utilizations in theselective transfer process. The receiving substrate may be, but is notno limited to, a printed circuit board (PCB), thin film transistorbackplane, integrated circuit substrate, or, in one case of opticalmicro devices such as LEDs, a component of a display, for example adriving circuitry backplane. Patterning a micro device donor substrateand receiver substrate can be combined—with different transfertechnology including but not limited to pick and place with differentmechanisms (e.g., electrostatic transfer head, elastomer transfer head),or a direct transfer mechanism such as dual function pads and more.

In one embodiment, the microdevices on donor substrates are patterned inclusters. The clusters may have a smaller pitch than the pixels on thereceiver substrate and the pitch on the receiver substrate may not be amultiple of the pitch of micro devices on the donor substrate. Thecluster can be the size of the pixel pitch of the receiver substrate.The area between each cluster is different from the micro device if thepitch of the pixel is not a multiple of the micro device pitch in thedonor substrate.

In another embodiment, the receiver substrate needs to be populated withdifferent types of micro devices and each pixel has different subpixelsfor different types of micro devices. To avoid transferring the wrongtype of micro devices to the subpixels, the donor substrate is dividedinto two areas in which, 1) if there are micro devices withoutinterfering areas with other micro device pads on the system substrateduring the transfer process, and 2) the areas that will interfere withother micro device pads on the system substrate if there is a microdevice in those areas.

In one embodiment the micro devices in the donor substrate only exist inthe areas without interference.

In one embodiment, the direction that the donor substrate is moved (orthe direction that the system substrate is moved) in reference to thesystem substrate (or in reference to the donor substrate) is used todefine the non-interfering areas and interfering areas.

In another embodiment, the subpixel pads for different micro devices areput close together, where the pad distance between at least two pads issmaller than the pitch of the pixel divided by the number of subpixels.In one case, the pitch between the pads of a subpixel in one pixel (oradjacent pixels) matches the donor substrate pitch (or is a multiple ofthe donor substrate pitch). It is possible that different donorsubstrates with different micro devices have different pitch. It ispossible that the pads for different micro devices have different sizes.The pad cluster for subpixel can be in different areas of a pixel inreference to the pixel area.

In one embodiment, the pad arrangement for different micro devices isaligned either vertically or horizontally.

In another embodiment the pads are aligned in both dimensions.

According to one aspect there is provided a method for integrated devicefabrication, where the integrated device comprises a plurality of pixelseach comprising at least one subpixel comprising a micro deviceintegrated on a substrate, and the method comprises: defining areas inthe donor substrate with and without interference areas with other microdevices pads, and minimizing the areas with interference to improvemicro device utilization.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other advantages of the disclosure will becomeapparent upon reading the following detailed description and uponreference to the drawings.

FIG. 1 shows an example of a micro device arrangement in a donorsubstrate.

FIG. 2 shows an example of a receiver substrate pixel with threedifferent sub pixels.

FIG. 3A shows an embodiment of a donor substrate that is arranged forinterference and non-interference areas based on the receiver substrate.

FIG. 3B shows another embodiment of donor substrate that is arranged forinterference and non-interference areas based on the receiver substrate.

FIG. 4 shows an embodiment using a taller pad associated with one of themicrodevices to improve the non-interfering area.

FIG. 5 shows a cluster pad embodiment to improve the non-interferingarea.

FIG. 6A shows a donor substrate embodiment with non-interfering areasassociated with the pads at the edge of the cluster pads.

FIG. 6B shows a donor substrate embodiment with non-interfering areasassociated with the inside pads of the cluster.

FIG. 7A shows an example of donor substrate and receiver substrate withcluster pads.

FIG. 7B shows another example of donor substrate and receiver substratewith cluster pads.

FIG. 8 shows an example of receiver substrates with pads in the pixelarranged in two directions.

FIG. 9A shows a donor substrate embodiment with non-interfering areaassociated with the one of the pads in the pixel.

FIG. 9B shows another donor substrate embodiment with non-interferingarea associated with the one of the pads in the pixel.

FIG. 9C shows another donor substrate embodiment with non-interferingarea associated with the one of the pads in the pixel.

FIG. 9D shows another donor substrate embodiment with non-interferingarea associated with the one of the pads in the pixel.

FIG. 10 shows an embodiment for cluster pads to improve thenon-interfering area for the pixel pads arranged in two directions.

FIG. 11A shows a donor substrate embodiment with non-interfering areaassociated with the one of the pads in the cluster.

FIG. 11B shows another donor substrate embodiment with non-interferingarea associated with the one of the pads in the cluster.

FIG. 11C shows another donor substrate embodiment with non-interferingarea associated with the one of the pads in the cluster.

FIG. 12A shows an example of a donor substrate and receiver substratewith cluster pads arranged in two directions.

FIG. 12B shows an example of a donor substrate and receiver substratewith cluster pads arranged in two directions.

FIG. 12C shows an example of a donor substrate and receiver substratewith cluster pads arranged in two directions.

FIG. 12D shows an example of a donor substrate and receiver substratewith cluster pads arranged in two directions.

FIG. 13A shows the pad cluster in a receiver substrate and a donorsubstrate embodiment with non-interfering area associated with referenceto one of the pads in the cluster.

FIG. 13B shows another donor substrate embodiment with non-interferingarea associated with the one of the pads in the cluster.

FIG. 14A shows an example of a donor substrate and receiver substratewith cluster pads arranged in two directions.

FIG. 14B shows an example of a donor substrate and receiver substratewith cluster pads arranged in two directions.

While the present disclosure is susceptible to various modifications andalternative forms, specific embodiments or implementations have beenshown by way of example in the drawings and will be described in detailherein. It should be understood, however, that the disclosure is notintended to be limited to the particular forms disclosed. Rather, thedisclosure is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theappended claims.

DETAILED DESCRIPTION

The process of transferring micro devices into a receiver substrateconsists of pre-processing the devices on a donor substrate (or atemporary substrate), preparing the landing area (or pads) on a receiversubstrate, transferring the micro devices from the donor to the receiversubstrate, and post processing to enable device functionality. Thepre-processing step may include patterning and adding bonding elements.The transfer process may involve bonding a pre-selected array of microdevices to the receiver substrate followed by removing the donorsubstrate. Several different selective transfer processes have alreadybeen developed for micro devices.

In this disclosure, pads in a receiver substrate refers to a designatedarea on a receiver substrate where a micro device is transferred. Thepads could be conducive to prepare a connection between the micro deviceand the pixel circuits or connections where the pixel circuits can beunderneath the pad or on the side of the pad. The pad could have someform of bonding materials to hold the micro device permanently. The padcan be a stack of multi-layers to offer a more mechanically stablestructure and also better functionality such as bonding and conductivitycapability.

The pads in this description can provide an electrical connection, amechanical connection or just a defined area to transfer micro devices.The shape of pads used in the embodiments are for illustration purposesand can have any arbitrary shape. The position of pads in respect to thepixels can be changed without affecting the embodiments. The orientationof the group of pads in the pixel can be changed. For example, they canbe rotated, shifted, or moved to different positions. The pads can havea complex structure consisting of different conductive, semiconductor,and dielectric layers. The pads can be positioned on top of otherstructures such as transistors in the receiver substrate. Also, the padscan be beside other structures on the receiver substrates.

The shape of micro devices used in the embodiments are for illustrationpurposes and devices can have different shapes. The micro devices canhave one or more pads on a side that will contact the receiversubstrate. The pads can be mechanical, electrical, or a combination ofboth.

In one embodiment, a method to arrange micro devices in the donorsubstrate is described that is used to transfer micro devices to thereceiver substrate. In the donor substrate, micro devices are arrangedin relation to the pixel area, and within the area associated with thepixel, the micro devices have a pitch that is smaller than the pixelpitch.

In this arrangement, the pitch between the micro devices at the boundaryof two pixels can be different from the pitch of micro devices withinthe pixel.

In this case, there are more micro devices in the donor substrate thanintended/wanted pads in the receiver substrate associated with the donorsubstrate. Therefore, the micro devices can interfere with otherunwanted/unintended pads in the receiver substrate. Several embodimentsin this document define interfering areas in the donor substrate toremove or prevent micro devices from populating those areas. Theseembodiments can be used for different micro device arrangements in thedonor substrate.

In another embodiment, a method of arranging the micro devices describedin the donor substrate to avoid interference with unwanted pads isprovided where the method includes:

-   -   a) defining non-interfering areas where:    -   1) the non-interfering areas are spaces in the donor substrate        that are not covered by other unwanted pads during micro device        transfer to the receiver substrate or    -   2) will not be covered by pads after offsetting the donor or        receiver substrate in a certain direction to align at least one        micro device with a wanted pad in the receiver substrate after        at least one micro device different from said micro device is        transferred to a pad that is different from the said pad in the        receiver substrate.    -   b) arranging micro devices in the non-interfering areas of the        donor substrate.

In the receiver substrate described above, one pad on the receiver canhave a taller structure and the micro device associated with said padhave a shorter structure. Thus, there will be no interfering area forthis pad.

To increase the non-interfering area, one embodiment is a method toarrange the pads associated with the micro device transfer position inthe receiver substrate to clusters, where, within said clusters, the padpitch is smaller than the subpixel pitch.

For cluster pads, a donor substrate for a pad at the edge of a clusteris arranged in such a way that interfering and non-interfering areas aresimilar to the pixel area, where the width of the interfering area isthe same as the distance of the other pads from said pad.

For a cluster, a donor substrate for a pad inside of a cluster isarranged whose interfering and non-interfering areas are similar to thepixel area and the interfering areas are defined as:

Finding the distance between the pad and the edge of said cluster pad.

Picking one micro device as a reference device in the donor substrate.

Defining the interfering area from the micro device to both sidessimilar to the distance of the associated pads to the edge of thecluster.

The pattern of interfering and non-interfering areas defined for an areaassociated with a pixel in a donor substrate can be repeated in a donorsubstrate similar to the pixel pitch.

In the remaining area of the donor substrate that is patterned(arranged) for the middle pad and associated with each pixel, a column(or row) of micro devices rests between interfering areas whose width islarger than the minimum distance of the middle micro device from theedge of said cluster.

In one embodiment to maximize the non-interfering area, the pad pitchwithin the cluster is the same as the micro device pitch in the donorsubstrate.

In another embodiment to maximize the non-interfering area, the pads arearranged in a two-dimensional cluster. The pads in the cluster can bealigned with at least one other pad.

In one embodiment, a donor substrate for the pads aligned with otherpads in two directions has diagonal interfering areas in reference tothe pad cluster orientations and the said area contains other pads andthe remaining area associated with a pixel is non-interfering in whichmicro devices can exist.

In another embodiment, a donor substrate for the pads is aligned withthe pads in only one direction and has interfering area as:

-   -   a) One row including other pads if the said pad is aligned        vertically with the other pads or;    -   b) One column if the said pad is aligned horizontally with        another pad.        And the remaining area associated with a pixel is        non-interfering in which micro devices can exist.

FIG. 1 shows a donor substrate arrangement 150 with more micro devicesthan associated pads in the receiver substrate. In this case, the microdevices have a smaller pitch 170 than the pixel pitch of the receiversubstrate in an area or block 130 of the donor substrate associated withthe pixels. Also, as the pixel pitch may not be a multiple of the microdevice pitch 170, the micro device pitch 180 between two pixel areas mayhave a different pitch to accommodate the difference between the pixeland micro device pitches.

In traditional pick and place, the microdevices on the transfer head(donor substrate 150) are transferred one at a time or one row at a timeto a position on the receiver substrate. To populate the rest of thereceiver substrate or another receiver substrate, the transfer headneeds to be repopulated or a new donor substrate 150 must be used. Thisprocess requires fast and accurate movement and precision alignmentevery time. This invention enables more microdevices 150 on the donorsubstrate than what is required to populate the receiver substrateequivalent area. Then, the donor substrate (or receiver substrate) isoffset to align the remaining set of micro devices with correspondinglocations in the receiver substrate. The offset can be doneindependently or it can be part of moving the donor substrate 150 to thenew location on the receiver substrate or a new receiver substrate.However, if the receiver substrate requires different micro devices thatare part of different donor substrates, the extra devices on a donorsubstrate can interfere with the location (pads) assigned to other typesof micro devices on the receiver substrate. This invention offersdifferent patterning for devices on the donor substrate to avoid suchissues.

FIG. 2 shows a pixel structure in a receiver substrate. The array can bemade of a different orientation and combination of this pixel structure.The pixel structure consists of different micro devices and each microdevice can have different pixel circuit or pixel connections. The pads204, 214, 224 for each microdevice type are put in each designatedsubpixel area 202, 212, 222. Here, the substrate shows three pads 204,214, 224 for three different micro devices. However, one can usedifferent micro devices. In one array structure, the micro device types(or subpixel type) only vary in one direction (one-directional arraystructure). In another array type, micro devices can vary in two or moredirections (multi-directional array). If the donor substrate for eachdevice type has micro devices in all the areas, micro devices in areascorresponding to the pads of the other micro device types can interferewith the pads during the transfer process. In one case, the only microdevices on the area related to its pads on the receiver substrate remainon the donor substrate. However, in this case the donor substrate needsto be replaced or refilled after each transfer which can reduce theprocessing step. Moreover, it can affect the micro device utilization ifthe reset of micro devices cannot be used. In one aspect of theinvention, the donor substrate for each micro device is divided intointerfering and non-interfering areas. The micro devices from theinterfering areas are removed or not populated. In one aspect of thisinvention, the micro devices are arranged in a donor substrate to avoidinterference with unwanted pads where the method includes:

-   -   a) defining non-interfering areas where:    -   3) the non-interfering areas are spaces in the donor substrate        that are not covered by other unwanted pads during micro device        transfer to the receiver substrate or    -   4) will not be covered by pads after offsetting the donor or        receiver substrate in a certain direction to align at least one        micro device with a wanted pad in the receiver substrate after        at least one micro device different from said micro device is        transferred to a pad that is different from the said pad in the        receiver substrate.    -   b) arranging micro devices in the non-interfering areas of the        donor substrate.

In one way to define these areas, the directions to offset a donorsubstrate (or receiver substrate) in relation to a receiver substrate(or donor substrate) are defined. For example, after a first set ofmicro devices are transferred from the donor substrate into the receiversubstrate, the donor substrate is offset horizontally and vertically.The other set of micro devices can be aligned with other related padsand transferred to these pads in a receiver substrate that can be theoriginal receiver substrate or a different one. The following procedureis an exemplary process that can be used to identify the interfering andnon-interfering area:

-   -   a) The first set of micro devices to transfer to the receiver        substrate is used as reference.    -   b) From the reference, micro devices draw lines in parallel with        the offsetting direction.    -   c) A line is drawn in the direction of offsets from the        corresponding pads for other types of micro devices in reference        to the reference pads on the donor substrate.    -   d) The closest lines from other types to the lines of the micro        device on the donor substrate are identified.    -   e) Draw a line between the selected lines and the micro device        line. This line has a similar distance from each of the micro        device lines and selected lines.    -   f) The areas defined by the new lines and encompassing the micro        device are the non-interfering areas. The other areas are        defined as interfering areas.

FIG. 3A shows one example of defining non-interfering area 304-1 andinterfering area 304-2. The pixel area 330 includes both areas. In thiscase, the micro devices are offset horizontally and vertically. As aresult, the width of the non-interfering area for each micro device isthe half of the sum of the distances between that pad 304 for that microdevice and the other adjacent pads 314, 324. In FIG. 3B, the devices areoffset horizontally and diagonally. As a result, the non-interferingarea has a slope similar to the slope of the diagonal offset process. Ascan be seen in both cases, the non-interfering area 304-1 is smallcompared to the interfering area 304-2.

One solution to address this issue is making one of the pads taller.This device can be the more expensive device or more used in thereceiver substrate. However, it can be any other device as well. In thiscase, the other micro devices should have a taller structure compared tothe micro devices associated with the taller pad. One method to achievea taller device is to have taller connection pads. The taller pad can beat either side of the device. FIG. 4 shows an exemplary receiversubstrate 400 where one of its pads 414 is taller than the other twopads 404, 424. Here, three different micro devices 404-D, 414-D, 424-Dare being transferred to the receiver substrate 400 from donorsubstrates 450-04, 450-14, 450-24. The micro devices 404-D, 424-Dassociated with the shorter pad structures 404, 424, have tallerstructures compared to the other micro device 414-D. The same techniquecan be applied to other combinations of micro devices (more or fewerthan three micro devices).

In another solution shown in FIG. 5 , the pads 504, 514, and 524 fordifferent micro devices are set in a cluster 540 close to each other. Inone embodiment, the circuit or other connections associated with thepads can be defined in the subpixel structures #1, #2, and #3 withwidths 508, 518, and 528, respectively, for ease of implementation. Inanother embodiment, the circuits and connections can have any otherstructure. The closer the pads are together, the larger thenon-interfering area 506 will be. In one case, the distance between twopads can be equal or smaller than ⅓ of the pixel pitch 530 for threedifferent micro devices (three different subpixels). For more or fewersubpixels (micro device types) the pads are also put closer together. Inone embodiment, the distance between the pads in the cluster is similarto the micro device pitch. If the different micro devices have the samepitch, the cluster pads will have the same pitch. In another case, thedistance between the pads in the cluster is a multiple of (for exampletwice) the pitch of the micro devices. In another embodiment, thedistance between the pads can be smaller than the pitch of the microdevices. FIG. 5 shows a receiver substrate with an example of padclusters 540. These pads 504, 514, 524 can be from the sub-pixels 502,512, 522 in one pixel 530 or from different pixels. These pads 504, 514,524 can be in any position in reference to the pixel 530. It is possiblethat the order and position of the pads 504, 514, 524 are different fordifferent pixels.

FIG. 6A shows the non-interfering area 604-1, and interfering area 604-2for the pad 604 at the edge of the cluster 640. The same structure canbe used for the other pad 624 at the other side of the cluster 640. Ascan be seen, the non-interfering areas for the pads at the edge arelarger compared to previous cases. For the pad 614 in the middle, thenon-interfering area 614-1 and interfering area 614-2 can be a stripepattern as demonstrated in FIG. 6B. Here, the width of the strip is thesame as the distance between the middle pad and the other pads. Todefine the non-interfering areas, the following steps can be used:

-   -   a) Find the distance between the pad and the edge of said        cluster pad    -   b) Pick one micro device as a reference device in the donor        substrate    -   c) Define the interfering area from the micro device to both        sides similar to the distance of the associated pads to the edge        of cluster.

The pattern of interfering and non-interfering areas defined for an areaassociated with a pixel in the donor substrate can be repeated in thedonor substrate similar to the pixel pitch.

In the remaining area of the donor substrate that is patterned(arranged) for the middle pad and associated with each pixel, a column(or row) of micro devices rests between interfering areas whose width islarger than the minimum distance of the middle micro device from theedge of said cluster.

If the distance between the middle pad and the other pads is the same,the ratio of interfering area 614-1 to non-interfering area 614-2 can bethe same. Similar to FIG. 3B, here the two areas can have differentshapes depending on the offsetting direction. Also, similar to FIG. 4 ,the middle pad can be taller and so in this case the non-interferingarea for the middle micro device can be the entire donor substrate.

If the micro devices do not have similar pitch, the distance betweenpads in the cluster can be similar to any of the pitches or each pad canhave a different distance from the other pads. To improve thenon-interfering area, the middle device can be the one with the largerpitch, and so using taller pads can help improve the interfering area.

FIG. 7 shows a case where the pads 704, 714, 724 in receiver substrate700 have the same pitch as micro devices in donor substrate 750. Theposition of pads cluster 740 can be different in reference to the pixels730. The size of pads can be smaller than, similar to, or larger thanmicro devices. The shape of the micro devices and pads can be anything.In this case, the micro devices are removed (or not populated) from theinterfering area on the donor substrate 750. FIG. 7A shows a case forthe edge pad 704 (similar structure can be used for 724). Some of microdevices 754 are already transferred and the donor substrate 750 (orreceiver substrate 700) is offsetted vertically in reference to receiversubstrate 700 (or substrate 750) so that another device is aligned withthe bare pads 704 (pads with no micro device transferred). It can bealso done horizontally. In this case, the empty space created bytransferring micro device 754 will be a new empty area which will be ontop of 714 and the empty space that was on top of 714 will be on top of724. As such there will be no interference caused by the micro devicesfor the unwanted pads 714, 724. One can finish all the micro devices inone column by offsetting vertically first and then moving to the nextcolumn (for example after finishing column 2, move to column 1). Howeverother combinations of vertical and horizontal offsetting can be used.The pixels 730 or the pad clusters 740 can be at an angle eithervertically or horizontally. In this case, the rows or the columns ofmicro devices will be tilted as well. In addition, the micro devices canbe at an angle without pads or pixels being at angles. In this case, theoffsetting direction will be toward the angle of the column or the row.FIG. 7B shows a similar structure of pad 704 in FIG. 7A for the middlepad 714.

FIG. 8 shows another pixel orientation example 850. Here, the subpixels802, 812, 822 are distributed in two dimensions. The pads 804, 814, 824are shown in each corresponding subpixel 802, 812, 822 area. Thedistance 816, 826, 836, 806 between the pads define the interfering andnon-interfering areas. The subpixels 802, 812, 822 can be aligned invertical and horizontal orientations (or diagonally). For example, 814and 824 can be aligned and so 826 can be zero.

FIG. 9 shows some examples for the interfering area and non-interferingareas for different pads. In FIG. 9A, the location of pad 904 is basedon horizontal and vertical offsetting of micro devices. In this case,the non-interfering area 904-1 and interfering area 904-2 can be acombination of boxes around or off from the pads 904, 914, 924. FIG. 9Bshows another example of the non-interfering area 904-1 and interferingarea 904-2 for pad 904. Here, the denominator of the two non-interferingareas between pad 904 and 914 and pads 904 and 924 is used as thenon-interfering area for pad 904. FIG. 9C shows horizontalnon-interfering area 924-1 and interfering area 924-2. For pad 914, themost optimized case is based on diagonal offsetting. FIG. 9D shows thediagonal strips for non-interfering area 914-1 and interfering area914-2. Other patterns also can be used with different offsettingdirections. Here, one can also use different pad heights as described inFIG. 4 to improve the device utilization for some of the pads.

FIG. 10 shows another example of cluster pad 1040 where the pads 1004,1014, 1024 are in two dimensions. Similar to FIG. 5 , the pads 1004,1014, 1024 can have a different pitch depending on different pitches ofmicro devices.

FIG. 11A shows the non-interfering area 1104-1, and interfering area1104-2 for the pad 1104 at the edge of the cluster 1140. As it can beseen, the non-interfering areas for the pads at the edge are largercompared to previous cases. FIG. 11B shows the non-interfering area1124-1 and interfering area 1124-2 for pad 1124. For the pad 1114 in themiddle, the non-interfering area 1114-1 and interfering area 1114-2 canbe a diagonal stripe pattern as demonstrated in FIG. 11C. Here, thewidth of the strip is the same as the distance between the middle padand the other pads. If the distance between the middle pad and the otherpads is the same, the ratio of interfering area 1114-2 tonon-interfering area 1114-1 can be the same. Similar to FIG. 3B, herethe two areas can have different shape depending on the offsettingdirection. Also, similar to FIG. 4, the middle pad can be taller and soin this case the non-interfering area for the middle micro device can bethe entire donor substrate.

FIG. 12 shows a case where the pads 1204, 1214, 1224 in receiversubstrate 1200 have the same pitch as micro devices in donor substrate1250. The position of the pads cluster 1240 can be different inreference to the pixels 1230. The size of the pads can be smaller orsimilar or larger than the micro devices. The shape of the micro devicesand pads can be anything. In this case, the micro devices are removed(or not populated) from the interfering area on the donor substrate1250. FIG. 12A shows a case for the edge pad 1204 . Some of the microdevices 1254 are already transferred and the donor substrate 1250 (orreceiver substrate 1200) is offsetted vertically in reference to thereceiver substrate 1200 (or donor substrate 1250) so that another deviceis aligned with the bare pads 1204 (pads with no micro devicetransferred). This can also be done horizontally. In this case, theempty spaces created by transferring micro device 1254 will be a newempty area which will be on top of other pads 1214, 1224. As such therewill be no interference caused by the micro devices for the unwantedpads 1214, 1224. One can finish all the micro devices in one column byoffsetting vertically first and then moving to the next column (forexample after finishing column 2, move to column 1). However othercombinations of vertical and horizontal offsetting can be used. Thepixels 1230 or the pad clusters 1240 can be at an angle eithervertically or horizontally. In this case, the rows or the columns ofmicro devices will be tilted as well. In addition, the micro devices canbe at an angle without pads or pixels being at angles. In this case, theoffsetting direction will be toward the angle of the column or the row.FIG. 12B shows a similar structure of pad 1204 in FIG. 12A for themiddle pad 1224. However, the interfering area with no micro device ishorizontal. FIG. 12C shows the donor substrate 1250 for the middle pad1214. Here, the interfering area is diagonal and the offsetting isdiagonal, vertical, and horizontal. FIG. 12D is a similar structure ofpad 1214 but with a slightly different arrangement for micro devices tomaximize the transfer.

FIG. 13A shows the non-interfering area 1304-1, and interfering area1304-2 for the pad 1304 at the edge of the cluster 1340 for a pixelwidth 1350 corresponding to a void area on a donor substrate. As it canbe seen, the non-interfering areas for the pads at the edge are largercompared to previous cases. The same pattern can be used for pad 1314.For the pad 1324 in the middle, the non-interfering area 1314-1 andinterfering area 1314-2 can be a vertical stripe pattern as demonstratedin FIG. 13B. Here, the width of the non-interfering area 1314-1 is thesame as the distance between the middle pad 1314 and the other pads1304, 1324 in the other pixel. If the distance between the middle padand the other pads is the same, the ratio of interfering area 1324-2 tonon-interfering area 1324-1 can be the same. Similar to FIG. 3B, the twoareas can have a different shape depending on the offsetting direction.Also, similar to FIG. 4 , one of the pads can be taller and so in thiscase the non-interfering area for the middle micro device can be theentire donor substrate.

FIG. 14 shows a case where the pads 1404, 1414, 1424 in receiversubstrate 1400 have the same pitch as micro devices in donor substrate1450. The position of pads cluster 1440 can be different in reference tothe pixels 1430. The size of the pads can be smaller or similar orlarger than the micro devices. The shape of the micro devices and padscan be anything. In this case, the micro devices are removed (or notpopulated) from the interfering area on the donor substrate 1450. FIG.14A shows a case for the edge pad 1404. Some of micro devices 1454 arealready transferred and the donor substrate 1450 (or receiver substrate1400) is offset vertically in reference to receiver substrate 1400 (ordonor substrate 1450) so that another device is aligned with the barepads 1404 (pads with no micro device transferred). This can] also bedone horizontally. In this case, the empty spaces created bytransferring micro device 1454 will be a new empty area which will be ontop of other pads 1414, 1424. As such there will be no interferencecaused by the micro devices for the unwanted pads 1414, 1424. One canfinish all the micro devices in one column by offsetting verticallyfirst and then moving to the next column (for example after finishingcolumn 2, move to column 1). However other combinations of vertical andhorizontal offsetting can be used. The pixels 1430 or the pad clusters1440 can be at an angle either vertically or horizontally. In this case,the rows or the columns of micro devices will be tilted as well. Inaddition, the micro devices can be at an angle without the pads orpixels being at angles. In this case, the offsetting direction will betoward the angle of the column or the row. FIG. 14B shows a similarstructure of pad 1404 in FIG. 14A for the middle pad 1414. However, theinterfering area with no micro device is horizontal.

The invention claimed is:
 1. A method of arranging micro devices in thedonor substrate, used to transfer micro devices to the receiversubstrate, where micro devices are arranged in relation to the pixelarea and the micro devices inside the area associated with the pixel hasa pitch that is smaller than the pixel pitch.
 2. The arrangement methodof claim 1, wherein the pitch between the micro devices at the boundaryof two pixels are different from the pitch of micro devices within thepixel.